It's a visual aid so you can see where you've already spread seed and a bulking material so the seeds are evenly distributed over a large area. It doesn't have to be sand, it's usually just some sort of lawn friendly material.
More and more individuals are contributing to the Internet through social media rather than simply consuming. They are bringing their (lack of) spelling and grammar with them, resulting in the variety of mistakes you've noticed.
At the same time I have noticed more and more mistakes appearing in "professional" publications. I don't ever recall seeing a typo on an NPR website up until the past 1-2 years. Now I see grammatical and spelling mistakes almost everywhere.
I'm guessing it's a combination of laying off editors and using AI.
But at the end of the day, if a language isn't evolving, it's dead.
Until you get pepper spray near the intake fan, then you're trapped in a spicy bubble.